Feeding mechanism for sewing machines



Nav. 15, 194

D. A. GRAESSER FEEDING MECHANISM FOR SEWING MACHINES 4 Sheets-Sheet 1 Filed April 10, 1947 INVENTGR David A uraesser BY f.,,'

I q ATTORNEY WITNESS Nov. 15, 1949 A, RA SSER 2,488,084

FEEDING MECHANISM FOR SEWING MACHINES Filed April 10, 1947 4 She'ebs-Sheet 2 1N VEN TOR BY j ATTORNEY Dav/dAGraesser Nov. 15, 1949- D, A, GRAESSER 2,488,084 I FEEDING MECHANISM FOR SEWING MACHINES Filed April 10, 1947 4 Sheets-Sheet 3 INVENTOR David/\fimesser WITNESS ATTORNEY 1949 D. A. GRAESSER FEEDING MECHANISM FOR SEWING MACHINES Filed April 10, 1947 4 Sheets-Sheet 4 mm W a Patented Nov. 15, 1949 FEEDING MECHANISM FOR SEWING MACHINES David A. Graesser, Westfield. N. J.,

, The Singer Manufacturing Company,

assignor to Elizabeth,

N. J a corporation of New Jersey Application April 10, 194:7, Serial No. 740,572

This invention relates to sewing machines and more particularly to those machines provided with feeding mechanism having means operable at the will of the operator for governing the amplitude and direction of work-feeding movements of the feeding element.

. It is the primary object of the present invention to provide a regulatable feeding mechanism which is well adapted for incorporation in a sewing machine having a pressure or splash lubri-' cating system.

Another object of the invention is to provide a feeding mechanism of which a major portion thereof can be assembled as a unit outside of the machine and then applied to the sewing machine through an opening in the machine-standard.

Other objects and attendant advantages will appear from the following description of the drawings, wherein Fig. 1 is a front elevation of a sewing machine embodying the invention, the bed of the sewing machine being sectioned longitudinally to show the usual feed-lift and feed-advance rock-shafts.

Fig. 2 is a bottom plan view of the sewing machine, illustrating the under-the-bed portion of the feeding mechanism.

Fig. 3 represents an enlarged vertical sectional view taken substantially along the line 3-3, Fig. 2.

. Fig. 4 represents a vertical sectional view, taken substantially along the line 4-4, Fig. 1, showing the feed-regulator set for maximum stitchlength, feeding forward.

Fig. 5 represents a sectional view taken substantially along the line 5-5, Fig. 4.

Fig. 6 represents a sectional view taken substantially along the line 6-6, Fig. 4.

Fig. '7 is a rear elevational view of the feedregulator supporting plate.

Fig. 8 is a top plan view of the feed-regulator supporting plate with the second or detachable bearing for the fulcrum-crank secured to its boss;

Figs. 9, l0 and 11 are diagrammatic views of the feeding mechanism, showing the fulcrumcrank in position for full forward feed (Fig. 9), in position for zero feed (Fig. 10), and in position for full reverse feed (Fig. 11)

Referring more in detail to the drawings, the invention is illustrated as applied to the lockstitch sewing machine having a frame including abed 2| from one end of which rises a standard 22 of an overhanging bracket-arm 23 terminating in a head 24. Journaled in suitable bearings in the bracket-arm 23 is a rotary mainor arm-' shaft 25 carrying at the standard-end thereof a balance-wheel 26 provided with a belt-groove 21 adapted to receive a belt (not shown) driven by any suitable power source. At the head-end, the

arm-shaft 25 has fast on it a counterbalanced crank 28 connectedby a link 29 to a reciprocatory 6 Claims. 4 (Cl. 112-210) needle-bar 30 carrying at its lower end an eye pointed thread-carrying needle 3|.

Cooperating with the needle in the formation of lock-stitches is a conventional rotary hook 32 (Figs. 2 and 3) secured on one end of a rotary bed-shaft 33 journaled in bearing lugs 34 and 35 depending from the bed 2|. The rotary shaft 33' is connected to be driven from the arm-shaft 25 by means of a vertical shaft 36 and the gearing 31, the ratio of the gearing being such that the bed-shaft 33 rotates at twice the speed of the arm-shaft 25. During the operation of the machine, the work is adapted to be clamped on the throat-plate 38 of the bed 2| by a presser-foot= 39 carried on the lower end of a presser-bar 40 journaled for endwise sliding movements in the head 24.

, The work is adapted to be fed past the stitching instrumentalities by means of a four-motion feeding mechanism. This mechanism includes a feed-dog 4| (Fig. 3) opposed to the presser-foot- 39 and secured to a feed-bar 42 connected at its forward end to a feed-lift rock-arm 43 clamped on the outer end of a feed-lift rock-shaft 44 supported by pintles 45 and an intermediate bearing 46 for oscillation about its longitudinal axis. The feed-lift rock-shaft 44 derives its oscillation from an eccentric 41 fast on the arm-shaft 25 through the medium of a pitman 48 embracing the eccentric 41 at its upper end and connected at its lower end to a rock-arm 49 preferably integral with the inner end of the feed-lift rock-shaft 44. Rotation of the arm-shaft 25 imparts to the feeddog 4| 2. given rising-and-falling movement to carry the feed-dog 4| up into and down out of engagement with the work supported on the bed 2|. As is usual in four-motion feeding mechanisms, advance-and-return movements are imparted to. the feed-dog 4| in proper time with the risingand-falling movements thereof in order to effect a substantially rectangular path of travel of the feed-dog. As a result of the feed-lift, a portion of the path of travel is above the level of the throat-plate 38 and is effective to feed the work relative to the needle, while another portion of the path of travel is below the level of the throatplate 38 and is effective to return the feed-dog 4|. By changing the amplitude of the advanceand-return strokes imparted to the feed-dog 4|,

the length of stitch can be varied and by reversing the direction of the advance-and-return strokes the feeding mechanism can be made to feed the Work backwardly. The present inven-' tion is directed to an improved mechanism whereby the operator may, at will, govern the amplitude and direction of work-feeding movements of the feed-dog 4|. Referring to Figs. 2, 3 and 4, it will be observed that the feed-bar 42 at its rear end is pivoted to the upper end of the spaced feed.

rocker limbs 50 and preferably integral with the outer end-portion of a feed-advance rockshaft 52-. At'its inner end the feed-advance rockshaft 52 has clamped thereon a rock-arm 53 to which is connected the lower end of a link 54. At its upper end the link 54 is connected to a knuckle-pin 55 to which is also pivoted the lower end of a pitman 56 embracing at its upper end an eccentric 57 preferably integral with the gear 31 (Fig. 5) which is fast on "the-arm-shaft 25.,

The pitman 56 and the link 54 are interconnected and the knuckle-pin 55 is constrained to move in a selected are. The opposite ends of the knuckle-pin 55 are carried in the spaced links 58, 59 of an anchor link 60 pivoted on a fulcrumpin :61 secured, as shown .in Fig. 6, in the side members of a U-shaped crank 62. The 'U-shaped crank 62 is formed with two aligned shaft-extensions 63 and 64 journaled in spaced bearings 65 and 66 provided ona removable cover-plate 61 attached by screws 68 to the front wall of the bracket-armstandard 22. To facilitate assembly, the bearing 66 for the shaft-extension 6 4 is formed in a detachable block-69 secured by screws 70 (Fig. 6) .to the cover-plate 61. The bearing 65 in the form of a bushing pressed into an aperture formed in the 'wall of an inwardly projecting lug H integral with the cover-plate 61. The lug II is hollowed out to provide a cavity 72 (Figs. 4, 5 and 6-) opening into the outer face of the cover-plate 61. Disposed to swing in the cavity 12 is a hand-operated regulating lever 13 of which the inner end is secured, as by a set screw 14 (Fig. 5), on the shaft-extension 63 of the U-shaped crank '62. Threaded on an extension of the regulating-lever 1311s a clamp-nut 76 which, when tightened, .bears against a springplate 17, forcing the spring-plate to grip a segmental plate 78 secured by screws 59 (Fig. 1) to the front of the cover-plate 61.

It will be understood from the above that by loosening the clamp-nut 16 the regulating lever 13 "may be moved, thus swinging the U-shaped crank 62 about the aligned axes of the shaftextensions 63 and 64. Movement of the crank 62 about the shaft-extensions 63 and 64 shifts the fulcrum pin 6-], resulting in a change in position of the are through which the knuckle-pin 55 swings. The effect of changing the location of the :are through which the knuckle-pin swings is clearly shown in Figs. 9, '10 and 11. In Fig. 9 it will be observed that when the eccentric 51 is rotated it will move the pitman 56 back and forth. The link 54 :and the anchor link 6!! are interconnected by means of the knuckle-pin '55 to form atoggle joint and, the fulcrum-pin 6| being held in set .position by the clamp-nut 16, the: knuckle-pin "is constrained to move in the .arc of a circle, indicated at A in Fig. 9. "The movement of the eccentric 5'! from the full line position to the dotted line position (Fig. 19) causes the links as and 55, through the rock-arm 53, to move the rock-shaft 52 in .a counterclockwise direction and thereby impart a feeding movement to the feed-dog "4|. With the parts positioned as shown in Fig. 9, the feeding mechanism is set to impart maximum forward feed.

'When the fulcrum-pin 51 is shifted from the position shown in Fig. 9 to the position shovm in Fig. 10, as by swinging the U-shaped crank 52, the knuckle-pin 55 is constrained to :move in the arc B. It will be seen that movement of the eccentric 5? from the full line position to the dotted line position causes the knuckle-pin 55 to swing an equal distance on :opposite sides of av from full line position to dotted line position will impart movement to the rock-shaft 52 in a clockwise direction, thereby imparting to the feed-dog 4| a feeding movement which is the reverse of the feeding movement illustrated in Fig. 9. It

- will be obvious from the above that the regulating lever 73 may be moved to cause the feeddog to feed the work either forward or backward and the throw or feeding movement of the feeddog may beregulated at will by simply adjusting the regulating JIBVQI' 73.

The feeding mechanism shown as applledsto, a pressure lubricated sewing machine of the type disclosed in U. S. 'Patent No. 2,206,285, issued on July 2, 1940, to R. Kaier. In this machine lu- 'bricant is introduced under pressure into the bore :of the arm-shaft and ducts communicating with the bore distribute the lubricant to the various bearingsurfaces. In the machine illustrated in the drawings, the arm-shaft 25 is provided with a longitudinal bore 80 (Fig. 5) into which oil is pumped in the manner shown in the above noted Kaier patent. Oil contained in the bore 80 is delivered by the radial ducts 8| and 82 into annular grooves 183 and 84 cut in the peripheryof the shaft 25. In communication with the groove 83 is a duct =85 formed in the feed-lift eccentric 41; the duct 85 serving to deliver oil to the periphery of the eccentric 41. The feed-advance eccentric 51 is provided with radial ducts 86in communication at their inner ends with the groove 84 in the arm-shaft 25 and at their outerends with an annular groove 87 in the periphery of the eccentric 51. Excess oil in the annular groove 81 is conducted by a 'hole '88 extending lengthwise of the pitman 56 to an annular groove 39 provided on the knuckle-pin 55, from which groove 89 the oil is led through the radial ducts 90 into a bore 9| drilled lengthwise of the knuckle-pin 55. Radial ducts in the knuckle-pin distribute the oil to the bearing of the link 54 and through the hole 92 (Fig. 6) in the anchorlink limb 59 to the fulcrum-pin 6|. Thus, it will be understood that all the bearing points in the feed-regulating means are adequately lubricated by oil under pressure. The construction of the cover-plate 61 is such that oil cannot escape and contaminate the front "of the machine-standard: 22. It will be apparent that oil cannot escape through the regulating-lever clearance slot in the segmental plate 18 for the reason that the shaft-extension 63 has a close bearing fit with the bushing 65 and consequently oil leakage through this working joint is negligible. A cap 93 pressed into the opening in the opposite wall of the lug 1! assists in providing an oil-seal forthe cavity 12.

To aid in determining whether sufficient oil is available for properly lubricating the machine, a sight-glass is employed behind which oil passes when the lubricating system is operating. To that end the cover-plate 61 (Figs. 1 and 4) is formed with an inclined inlet duct 93' terminating at its outer 'end in a recess 94 covered by a: sight-glass 95 held in place by a plate 96 aperturedaasat '911and.-fastenedito the cover-plate 61 by the screws 98. ;Oil, after :passing behind thesight-glass 95, is returned within the standard 22 by the outlet port 99. As fully disclosed in the Kaier Patent No. 2,206,285, oil that is splashed into the inlet duct 93 is excess oil thrown off of the gear 31 which is fast on the arm-shaft 25.

From the foregoing description considered in connection with the accompanying drawings, the construction, manner of operation and several advantages of my improved feeding mechanism will be clearly and fully understood. It is apparent that the component parts of the feed regulating means are compactly and sturdily arranged and that lubrication can be distributed to all the bearing surfaces, insuring long life and ease of operation. It will be appreciated also that the feed regulating means, including the pitman 56 and the link 54, can be assembled as a unit and then conveniently applied to the machine through the large opening in the standard 22.

Having thus set forth the nature of the invention, what I claim herein is:

1. A sewing machine having a frame provided with an opening, a cover-plate for closing said opening, a feed-bar, a feed-dog carried thereby, means for imparting rising-and-falling movements to said feed-dog, a feed-rocker connected to said feed-bar, a rock-shaft supporting said feed-rocker, a rotary shaft, an eccentric carried by said shaft, a pitman actuated by said eccentrio, a single link connecting said pitman to said rock-shaft, an anchor-link for controlling the path of movement of the connection between said pitman and said first mentioned link, a fulcrumpin pivotally supporting said anchor-link, a crank member mounted on said cover-plate and carrying said fulcrum-pin, and manual means for turning said crank member to vary the set position or said fulcrum-pin.

2. A sewing machine having a frame formed with a lubrication compartment having an opening therein, a cover-plate for closing said opening, a feed-bar, a feed-dog carried thereby, means for imparting rising-and-falling movements to said feed-dog, a feed-rocker connected to said feed-bar, a rock-shaft supporting said feed-rocker, a rotary shaft, an eccentric carried by said shaft, a pitman actuated by said eccentric, a single link connecting said pitman to said rock-shaft, an anchor-link for controlling the path of movement of the connection between said pitman and said first mentioned link, a fulcrum-pin to which said anchor link is pivoted, a crank member supporting said fulcrum-pin and having a shaft-extension turnable in an oiltight Joint in said cover-plate, and manual means for turning said crank member to vary the set position of said fulcrum-pin.

3. A sewing machine having a frame provided with an opening, a cover-plate for closing said opening having a supporting lug projecting from one face thereof, said lug being hollowed out to provide a cavity opening into the other face of said cover-plate, a feed-bar, a feed-dog carried thereby, means for imparting rising-and-falling movements to said feed-dog, a feed-rocker connected to said feed-bar, a rock-shaft supporting said feed-rocker, a rotary shaft, an eccentric carried by said shaft, a pitman actuated by said eccentric, a link connecting said pitman to said rock-shaft, an anchor-link for controlling the path of movement of the connection between said pitman and said first mentioned link, a fulcrumpin to which said anchor-link is pivoted, a crank member supporting said fulcrum-pin and having a shaft-extension journaled in and extending through at least one wall of said cover-plate supporting lug and into said cavity, and a lever means secured to said shaft-extension and operable in said cavity for turning said crank member to vary the set position of said fulcrum-pin.

4. A sewing machine having a frame provided with an opening, a cover-plate for closing said opening having spaced supporting lugs extending from the inside face thereof with one of said lugs being hollowed out to provide a cavity opening into the outer face of said cover-plate, a feed-bar, a feed-dog carried thereby, means for imparting rising-and-falling movements to said feed-dog, a feed-rocker connected to said feed-bar, a rockshaft supporting said feed-rocker, a rotary shaft, an eccentric carried by said shaft, a pitman actuated by said eccentric, a link connecting said pitman to said rock-shaft, an anchor-link for controlling the path of movement of the connection between said pitman and said first mentioned link, a fulcrum-pin to which said anchor-link is pivoted, a crank member supporting said fulcrum-pin and having aligned shaft-extensions journaled in the spaced supporting lugs of said cover-plate, and a lever secured to one of said shaft-extensions and operable in said cavity for turning said crank member to vary the set position of said fulcrum-pin.

5. A stitch-length regulating unit for sewing machines having a feed-advance rock-shaft and a rotary shaft fitted with an actuating eccentric, comprising a supporting plate, a crank member pivoted, to said supporting plate, a fulcrum-pin carried by said crank member, an anchor-link pivoted on said fulcrum-pin, a knuckle-pin carried by said anchor-link, a second link connected at one end to said knuckle-pin and adapted to be connected at its other end to said feed-advance rock-shaft, a pitman connected at one end to said knuckle-pin and adapted to be connected at its other end to said actuating eccentric, and means for turning said crank member to vary the set position of said fulcrum-pin.

6. A stitch-length regulating unit for sewing machines having a feed-advance rock-shaft and a rotary shaft fitted with an actuating eccentric, comprising a supporting plate, a U-shaped crank member having aligned shaft-extensions journaled in said supporting plate, a fulcrum-pin carried by said crank member, a U-shaped anchor-link pivoted on said fulcrum-pin, a knucklepin secured in the limbs of said U -shaped anchorlink, a second link connected at one end to said knuckle-pin and adapted to be connected at its other end to said feed-advance rock-shaft, a pitman connected at one end to said knuckle-pin and adapted to be connected at its other end to said actuating eccentric, and a manually controlled lever for turning said crank member about the axes of the shaft-extensions to vary the set position of said fulcrum-pin.

DAVID A. GRAESSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 623,271 Allen Apr. 18, 1899 2,381,685 Parry Aug. 7, 1945 FOREIGN PATENTS Number Country Date 461,922 Germany June 30, 1928 

